Conventional robotic applications impart multi-axis rotational motion to a robotic end-effector by using multiple separate independent drive mechanisms. Typically, three servo motors represent three independent joints for a robotic arm. Usually, each servo motor independently can provide approximately 270.degree. (degrees) of rotation about a single axis, which constitutes a portion of the total rotational motion imparted on the robotic end-effector. A combination of an X-axis motor, a Y-axis motor, and a Z-axis motor can impart a three dimensional motion to the robotic end-effector.
In an alternative application, there are known frictional drive mechanisms that can move a spherical joint. These frictional drive mechanisms typically comprise multiple wheels movably coupled, e.g., via surface friction, to a spherical joint to impart multi-axis rotational motion to the spherical joint. Each wheel typically rotates about an independent axis, and the combination of wheels, or frictional drive mechanisms, can impart multi-axis rotational motion to the spherical joint.
Both of these alternatives require separate multiple independent drive motors to accomplish the multi-axis rotational motion. In the first case, three independent servo motors accomplish the multi-axis rotational motion at the robotic end-effector. In the latter case, two or three independent motors may drive the wheels to frictionally impart the multi-axis rotational motion to the spherical joint.
Thus, what is necessary is a simpler method and apparatus for imparting multi-axis rotational motion.